About Go — 2 Player
Two players, one screen: pass the device after every move. Pick a 9×9 board for a quick game, 13×13 for a longer one, or the full 19×19 board. Black moves first and White receives 7.5 points of komi.
Go is the ancient board game of surrounding territory. Two players take turns placing black and white stones on the lines of a grid, trying to wall off more of the board than the other. Stones that are completely surrounded are captured. The rules fit on a postcard, and the strategy lasts a lifetime.
Also called: baduk, weiqi, igo.
How to play Go
- Black moves first. On your turn, place one stone on any empty intersection of the lines, or press Pass. Stones never move once placed.
- The empty points next to a stone, along the lines, are its liberties. Stones of one colour that touch along the lines form a string and share their liberties.
- Take away a string’s last liberty and it is captured: the stones come off the board. The counts under each name show how many stones each side has taken.
- On a phone, the first tap shows a ghost stone and a second tap on the same point places it. With a mouse, click once. Arrow keys and Enter work too, and P passes.
- When neither player can gain anything more, both pass. The game then shows which stones it thinks are dead (they turn grey) and whose area every point is. Tap a group to mark it dead or alive, then press Accept score, or Resume play if you disagree.
Rules
- Area scoring: your score is your stones on the board plus the empty points surrounded only by your stones. Dead stones are removed first and their points count for the side that surrounds them.
- Komi: White gets 7.5 points to make up for moving second. The half point means a game can never be drawn.
- No suicide: you can’t place a stone where it (and any string it joins) would have no liberties, unless the move captures something, which frees up liberties.
- Ko: if your opponent has just captured a single stone, you may not immediately recapture it by playing back on that point. Play somewhere else first. A small dashed square marks the ko point.
- Positional superko: no move may recreate any board position (the arrangement of stones, whoever is to move) that has already appeared in the game. This settles the rare long cycles, such as triple ko, that simple ko misses.
- Two passes in a row end play. Resigning ends the game at once.
Go tips and strategy
- Corners first, then sides, then the centre. A corner needs the fewest stones to surround, so it is the cheapest territory on the board.
- A group needs two eyes to live. An eye is an empty point surrounded by your stones. A group with two separate eyes can never be captured, because your opponent can’t fill both at once.
- Count liberties in a fight. When two groups are pressing on each other, the one with more liberties usually wins. Look for moves that take away your opponent’s liberties while adding to yours.
- Don’t chase every stone. Keeping your own groups connected is usually worth more than capturing one or two stones.
- Before you pass, check that every border between your area and your opponent’s is closed. Under area scoring, filling a neutral point between the two walls is worth a point.
Go questions
Why is White given 7.5 points?
Moving first is an advantage worth about seven points on a 9×9 board. The 7.5 komi balances it, and the half point means someone always wins.
What is the difference between ko and superko?
Simple ko only stops you retaking a single stone straight back. Positional superko goes further: no move may bring back any earlier board position at all. In almost every game the two rules agree; superko just stops the rare endless cycle.
How are dead stones decided?
When both players pass, the game plays the position out many times in the background and marks the strings that are captured in most of those games as dead. It is usually right, but not always, so either player can tap a group to change it before accepting the score.
How strong is the computer?
It uses Monte Carlo tree search in a background thread, playing thousands of quick games to the end and keeping the moves that win most often. Easy looks at about a hundred games per move, Normal thinks for about a second and Hard for two to three seconds. Normal comfortably beats a beginner; Hard gives a newer player a real fight.
Is my game saved?
Yes. Every move is saved in your browser, so you can close the tab and carry on later. Your wins against each computer level, and the Black and White wins on the same-screen board, are kept too.
Is Go free to play?
Yes. Go on Kultured Arcade is completely free: no download, no account and nothing to buy. It runs in any modern browser on a phone, tablet or computer.
Do I need to download Go?
No. It opens instantly in your browser and saves your progress on your device, so there is nothing to install and no sign-up.
Can I play Go on my phone?
Yes. The game fits your screen and works with touch as well as a mouse and keyboard, on iPhone, Android, tablets and computers.
Can I play Go online with a friend?
Yes. Open the Online tab and choose Create invite, then send the link or the six-character code. The game starts as soon as your friend opens it. Quick match pairs you with someone who is waiting.